German Bank Survey # 6 Results from 11/10/2023
Survey Details
5 commercial purse seiners conducted this fishing survey on 11/10/2023 starting at 20:00:00.
All vessels ran two transects in the German Bank box and one transect in the Seal Island Box.
There was a plankton tow and replicate conducted and CTD cast by Lady Janice II.
No tags were applied during this survey.
Samples were obtained for target strength estimation.
Acoustic Equipment
Each vessel was equipped with a Simrad ES38-18/200-18C combi (2-in-1) transducer prior to the survey that contains a 38kHz split beam and 200 kHz single beam transducer. Data was logged to the computer hard-drive for post-processing. All participating boats were calibrated on 38kHz before the survey.
Survey Results
Main Results
The results are subject to change as DFO will re-evaluate data editing, area estimation and apply a target strength.
Preliminary biomass prediction for German Bank using standardized parallel transects is 23,614mt, and with turnover applied 20,057mt. The preliminary biomass estimate for Seal Island is 15,261mt.
Transect Details
| Vessel | Transect # | Date/Time Start | Date/Time End | Start Lon | Start Lat | End Lon | End Lat | Location | Distance (km) | Speed |
|---|---|---|---|---|---|---|---|---|---|---|
| C1 | T01 | 2023-10-11 23:54:09 | 2023-10-12 02:21:24 | -66.409 | 43.566 | -66.407 | 43.237 | GB | 39.21 | 8.63 |
| C1 | T02 | 2023-10-12 02:55:49 | 2023-10-12 05:20:20 | -66.267 | 43.237 | -66.268 | 43.566 | GB | 38.94 | 8.73 |
| C1 | T03 | 2023-10-12 05:54:31 | 2023-10-12 07:44:29 | -66.151 | 43.502 | -66.151 | 43.246 | GB | 30.24 | 8.91 |
| LB | T01 | 2023-10-11 23:40:10 | 2023-10-12 02:23:09 | -66.437 | 43.566 | -66.437 | 43.235 | GB | 38.25 | 7.60 |
| LB | T02 | 2023-10-12 03:04:51 | 2023-10-12 05:34:52 | -66.296 | 43.234 | -66.296 | 43.567 | GB | 38.09 | 8.23 |
| LB | T03 | 2023-10-12 06:14:45 | 2023-10-12 08:03:21 | -66.178 | 43.504 | -66.178 | 43.247 | GB | 29.38 | 8.77 |
| LJ | T01 | 2023-10-11 23:48:11 | 2023-10-12 02:13:19 | -66.381 | 43.567 | -66.381 | 43.234 | GB | 37.00 | 8.26 |
| LJ | T02 | 2023-10-12 02:49:46 | 2023-10-12 05:12:10 | -66.240 | 43.233 | -66.239 | 43.568 | GB | 37.33 | 8.49 |
| LJ | T03 | 2023-10-12 05:47:27 | 2023-10-12 07:37:19 | -66.125 | 43.503 | -66.125 | 43.245 | GB | 28.71 | 8.46 |
| MS | T01 | 2023-10-11 23:49:25 | 2023-10-12 02:28:36 | -66.493 | 43.563 | -66.493 | 43.237 | GB | 39.06 | 7.95 |
| MS | T02 | 2023-10-12 03:10:15 | 2023-10-12 05:30:16 | -66.352 | 43.237 | -66.353 | 43.563 | GB | 38.18 | 8.83 |
| MS | T03 | 2023-10-12 06:06:52 | 2023-10-12 07:50:21 | -66.229 | 43.501 | -66.230 | 43.252 | GB | 29.21 | 9.14 |
| SL | T01 | 2023-10-12 00:47:24 | 2023-10-12 03:13:58 | -66.465 | 43.567 | -66.465 | 43.233 | GB | 40.51 | 8.95 |
| SL | T02 | 2023-10-12 03:58:25 | 2023-10-12 06:25:37 | -66.324 | 43.235 | -66.325 | 43.568 | GB | 39.28 | 8.64 |
| SL | T03 | 2023-10-12 07:05:51 | 2023-10-12 08:51:49 | -66.202 | 43.500 | -66.204 | 43.246 | GB | 30.19 | 9.23 |
Survey Summary
| Vessel | Transect No. | Target Strength (db/kg) | Mean Sa (/m2) | Biomass Density (kg/m2) |
|---|---|---|---|---|
| LJ | T03 | -35.5 | -42.373 | 0.205 |
| MS | T01 | -35.5 | -42.969 | 0.179 |
| LB | T03 | -35.5 | -48.266 | 0.053 |
| MS | T02 | -35.5 | -51.108 | 0.027 |
| C1 | T03 | -35.5 | -52.979 | 0.018 |
| LB | T02 | -35.5 | -53.028 | 0.018 |
| LB | T01 | -35.5 | -53.518 | 0.016 |
| SL | T02 | -35.5 | -54.328 | 0.013 |
| C1 | T01 | -35.5 | -55.033 | 0.011 |
| SL | T01 | -35.5 | -55.165 | 0.011 |
| LJ | T01 | -35.5 | -56.422 | 0.008 |
| LJ | T02 | -35.5 | -56.764 | 0.007 |
| SL | T03 | -35.5 | -58.519 | 0.005 |
| MS | T03 | -35.5 | -58.520 | 0.005 |
| C1 | T02 | -35.5 | -59.433 | 0.004 |
| Note: | ||||
| Transects are listed from greatest to least backscatter. |
| Layer | Target Strength | Area (km2) | Mean Sa | Density (kg/m2) | Biomass (tons) | Percent Area | Percent Biomass | Standard Error (tons) | Standard Error (%) |
|---|---|---|---|---|---|---|---|---|---|
| German Bank | -35.5 | 796 | -50.7775 | 0.0295 | 23,613.68 | NA | NA | 13,334.58 | 56.47 |
| Seal Island | -35.5 | 272 | -48.0098 | 0.0572 | 15,261.26 | NA | NA | 10,357.46 | 67.87 |
| School Survey | NA | NA | NA | NA | NA | NA | NA | NA | NA |
Greatest Biomass Densities
A snip from the transect with the greatest biomass density (kg/m2)
The single point with the largest biomass density (kg/m2) was recorded by MS, at the following location:
The transect with the greatest average biomass density (kg/m2) was recorded by LJ, at the following location:
Annual Summaries
|
Current Year
|
Previous Year
|
||||||||
|---|---|---|---|---|---|---|---|---|---|
| Ground | Survey Number | Survey Date | HSC Estimate | HSC Turnover Adjusted | Survey Date | HSC Estimate | HSC Turnover Adjusted | DFO Estimate | DFO Turnover Adjusted |
| German Bank | 1 | 2023-08-06 | 2,686.514 | 2,686.514 | 2022-08-14 | 16,285 | 16,285 | 22,081 | 22,081 |
| German Bank | 2 | 2023-08-20 | 4,930.454 | 4,406.486 | 2022-08-28 | 7,472 | 4,296 | 11,699 | 7,393 |
| German Bank | 3 | 2023-09-03 | 9,959.441 | 8,901.000 | 2022-09-11 | 12,507 | 10,464 | 11,902 | 8,826 |
| German Bank | 4 | 2023-09-13 | 16,265.846 | 13,203.000 | 2022-09-25 | 15,924 | 13,216 | 12,503 | 9,761 |
| Seal Island | 1 | 2023-08-06 | 1,205.361 | NA | 2022-08-14 | 2,598 | 2,598 | 2,086 | 2,086 |
| Seal Island | 2 | 2023-08-20 | 1,917.847 | NA | 2022-08-28 | 1,048 | 1,048 | 570 | 570 |
| Seal Island | 3 | 2023-09-03 | 2,062.584 | NA | 2022-09-11 | 6,941 | 6,941 | 6,392 | 6,392 |
| Seal Island | 4 | 2023-09-13 | 5,635.715 | NA | 2022-09-25 | 4,634 | 4,634 | 3,732 | 3,732 |
| German Bank | 5 | 2023-09-27 | 15,241.681 | 11,360.000 | 2022-10-10 | 19,539 | 16,337 | 20,247 | 17,675 |
| Seal Island | 5 | 2023-09-27 | 53,843.744 | NA | 2022-10-10 | 5,243 | 5,243 | 5,604 | 5,604 |
| German Bank | 6 | 2023-10-11 | 23,613.676 | 20,057.000 | 2022-10-23 | 13,399 | 8,684 | 15,565 | 10,823 |
| Seal Island | 6 | 2023-10-11 | 15,261.261 | NA | 2022-10-23 | 2,944 | 2,944 | 3,260 | 3,260 |
| Year | Ground | HSC Estimate | HSC Turnover Adjusted | DFO Estimate | DFO Turnover Adjusted |
|---|---|---|---|---|---|
| 2022 | German Bank | 85,126.00 | 69,282 | 93,997 | 76,559 |
| 2022 | Seal Island | 23,408.00 | 23,408 | 21,644 | 21,644 |
| 2023 | German Bank | 72,697.61 | 60,614 | NA | NA |
| 2023 | Seal Island | 79,926.51 | NA | NA | NA |
Tagging, Plankton, and CTD Data
Tag Data
| Vessel | Tags |
|---|---|
Plankton Data
Tow Summary Table
|
Tow 1
|
Tow 2
|
|
|---|---|---|
| Base Details | ||
| Vessel | Lady Janice II | Lady Janice II |
| Set Number | GB2023-11 | GB2023-12 |
| Ground | GB | GB |
| Date | 11/10/2023 | 11/10/2023 |
| Wind Direction (km/h) | NW | NW |
| Swell (m) | 0.5 | 0.5 |
| Air Temp (c) | 12 | 12 |
| Tow Details | ||
| Tow Start | 19:01:00 | 19:17:00 |
| Tow End | 19:17:00 | 19:27:00 |
| Start Lat | 43.57306 | 43.57750 |
| End Lat | 43.57000 | 43.57083 |
| Start Lon | -66.35972 | -66.37083 |
| End Lon | -66.37361 | -66.36806 |
| Avg Tow Depth (m) | NA | NA |
| Speed | 2.1 | 1.5 |
| Heading | 248.0 | 0.3 |
| Tide Direction | with | against |
| Other Data Collection | ||
| Flow Start | 594023 | 616254 |
| Flow End | 616254 | 645863 |
| No. Revolutions | 22231 | 29609 |
| Distance (m) | 597.4137 | 795.6827 |
| Volume | 1876.775 | 2499.637 |
| Secchi Disappear (m) | 7 | 7 |
| Secchi Reappear (m) | 6 | 6 |
Tow Depth Profiles
Plankton tow depth profile #1
Plankton tow depth profile #2
The first tow is GB2023-11, which was with the tide and had an average depth of NAm. The second tow is GB2023-12, which was against the tide and had an average depth of NAm.
Captured plankton
Captured plankton from the surface tows
CTD Data
CTD depth profiles for all 2023 German Bank surveys so far.
Sea surface temperatures
Annual average sea surface temperatures (SST) for German Bank.
Vessel Performance
Speed
Average vessel speed was 8.59. This is above the 8 knot requirement; vessels are urged to slow down to prevent backscatter noise from interfering with the acoustic data.
Distance
No significant distance was cut from the planned lines; vessels covered the planned area well.